Ignition coil testing

[BuzzStPoint]

I've heard you can test coils via MultiMeter.

Chrysler 55hp
Magneto engine.
Model: 555HA
Serial: x4949
Year 1970

I dont know how to test it, but from Plug wire to both red wires coming from coils gives a reading.
Coil 1: 6.05 ohm
Coil 2: 5.87 ohm

These readings correct?

The engine starts, but we found the upper plug not firing. Lower plug would fire but cut out for a bit. With some poking around I found the upper plug to have a loose connection at the plug boot. That has been repaired.


Plus is there a way to test the condensers?

 

[wickware]

Re: Ignition coil testing

There are coil/condenser testers. I have found less than 5 of each bad since 1968 (other than the ones leaking or corroding). In most cases I have found bad points in the magneto system due to burned/pitted, dirty, bad gap adjustment. In my opinion, it?s hard to justify the cost of a coil/condenser testers back then and possibly now (w/o a large volume and variety of work). Using a known good (used or new) condenser or coil (if you have eliminated all other possibilities) are good testers.

The tester I experienced:

1. Would give you a specific microfad reading of your condenser to see if it?s in the good range.

2. Would energize your coil to fire your plug or a simulated plug and check other specs.

I noticed info on the net on ?how to test a lawn mower condenser or coil? (basically the same Magneto System). I hope this helps. Please share info on the conditions and gaps of your points. Good Luck! JOW

 

[BuzzStPoint]

Re: Ignition coil testing

I pulled the system apart.

Cleaned the points, (nobody has points and condensers here in town.

A timing light shows when cranking that I have spark . I found 1 ground that was chaffed, and the plug ends corroded.

I think I'm having trouble setting the points/timing.

One book I found stays to put the stator plate to WOT and align the cam mark to the breaker follower. Set to .020
Done this on both points.

When I try to start. All I get is back fires (Through exhaust)

I'm not sure whats going on..
Any tips for this outboard?


Another question on Flywheels. How to tell if they are bad?
I heard take a screw driver and touch the magnets on both side of the the flywheel. If they stick they are good. I've done this and only one side sticks. The opposite side there is no magnetism.

 

[wickware]

Re: Ignition coil testing

Hopefully I can help with a few points until the updated Techs and info comes. I crossed over to my 1970 35 HP Chrysler (which should be the same as your 55 HP) from my small engine repairs (mainly lawn mowers). Over the years I have learned to be ?Slow To No? on making adjustments I do not have experience on (timing on Tecumseh engines mainly which I feel relates to this model Chrysler). What is the history of the engine? Was it running fine recently or has it been sitting a few seasons/years? Did you pull the points to clean them? Did you change the timing? Have you adjusted the points and timing with good results before? I hate asking the questions and I hope they are not offending you. I know setting the points and timing takes some experience. The process gets old in my opinion if it?s not done every few years.

What all did you take apart (if not already answered)? What position was the piston in when you set your points? Do you have the tool or a dial indicator to know the position of your piston (TDC, 32 BTDC or Etc.)?

I am not familiar with your flywheel testing or the proper procedure.

JOW

 

[BuzzStPoint]

Re: Ignition coil testing

No offense taken..

History of the motor? Unknown.
Only had it running this spring in a barrel.

I actually got it fired up and firing on both cylinders.
I was running good till we brought it to the landing. Found no reverse.
I pulled the flywheel and pulled everything off the stator plate. Cleaned the points.

TO adjust the point, I followed a manual I have on PDF. Throttle at WOT then I turned the crankshaft till the cam mark was on the front edge of the points follower. Then adjusted the points to 0.020. Did both point sets like that.
I cleaned all wire connections.
But at the dock is started it bucking and missing again. I'm thinking the Points and condensers are faulty. I'll have to order those.

I don't have that tool to set the timing.

But I have a linkage issue that I will start a new thread.

 

[wickware]

Re: Ignition coil testing

The unknown history and moving a lot at one time could give you a good challenge (unless you have good to fair experience). I have owned my 1970, 35 HP Chrysler since 1985. I might have changed the points initially but have only cleaned them since w/o pulling them. My points have only been dirty vs burned/pitted. Slight hesitation or bogging during a fast accelerating usually lead me to my points. I have not had to adjust my timing or had any timing related issues. I know about adjusting points from servicing late 60s and early 70 VW beetles.

Are the coils adjustable on the stator plate? This could account for a weak to no spark if the gap between the flywheel and coil is not correct. Setting the points to the correct gap with the piston in the correct position is probably causing your backfire. Without a tool to set the timing it will take some trial and error. Knowing TDC, BTDC and converting you flywheel teeth to degrees related to a fixed mark should get the job done.

One last question to you and others that I should know. Is there a crank or cam mark related where the points should be set and is the cam opening the points at the highest point at this mark?

Again, I hope I?ve been some help and will look forward to others info toward helping you.

JOW

 

[BuzzStPoint]

Re: Ignition coil testing

the coils are non adjustable. So if thats the issue, then it would be a flywheel issue. As for points mark. Yes, on the shaft where the points ride on, there is a mark there that shows the setting.

I'm going to try to find a set of points and condenser and see if that will sort out the missing and backfiring.

 

[wickware]

Re: Ignition coil testing

Have you tried to determine where your timing is set now? Watching the points, you should be able to tell if they are opening at TDC or BTDC (by feeling the piston travel through the spark plug hole). Counting the total number of teeth on your flywheel and divide that number into 360 should give you approximately how many degrees each tooth's point represents. A fixed mark on the block and knowing what a tooth represents should get you close enough to 28-32 degrees BTDC to know you are in the ball-park or closer (to stop the backfiring). A wink from your timing light compared to a fixed mark compared to TDC and the fixed mark should give you an idea as to where your timing is set???

Hopefully someone that has used this method will share some info. I would hate to see you spend money on points and condensers if they are not the problem. Does the motor start fairly easy and idles ok and the backfiring is when you accelerate? Have you tried tweaking the timing or have any close reference of where it was set? From your stated history, it seems the motor was running better before the adjustments were made. To me, this would say something in the adjustments is possibly the problem. Most of all, d/n run it too long or hard out of time and cause damages to the motor.

Hello Friends, Please Help Us With Some Advice. JOW

 

[BuzzStPoint]

Re: Ignition coil testing

It was running excellent yesterday till we started messing with the linkage. Then it popped and started the studdering. It doesn't backfire anymore.

As for starting.. Pops right off.

I have to regap the points, I pulled the condensor and points out to run them down to the marine shop. But they didn't have a points set to match up..

How ever, I think I may have found the issue. When I pulled the flywheel off this time the flywheel key was sheared off. The marine store had 2 keys so I bought them.

Since I have to regap, I'll try your method of timing the engine and see if that helps.

 

[wickware]

Re: Ignition coil testing

Good News! I should have mentioned the key when I referenced to causing more damage. A backfire has to be hard on a key. How many ft lbs. are you torquing the flywheel?

When I saw your post related to shifting gears I took this as the motor was running better. I?ll jump on that post and try to share some of my experiences. JOW

 

[wickware]

Re: Ignition coil testing

Scratch the wink info. ?A wink from your timing light compared to a fixed mark compared to TDC and the fixed mark should give you an idea as to where your timing is set???? I should be referring to Static Timing using a volt/ohm meter or test light that will indicate the exact time the points open etc.. The timing light is used in a running mode (Dynamic Timing). These procedures (as others) get old when they are not used periodically (to keep you mentally tuned). JOW

 

[BuzzStPoint]

Re: Ignition coil testing

It was running nice, then stopped that day at the dock..

I have it running real nice now..
Turned out I did shear the flywheel key.
Replaced the key set the gaps, then had a random mis in the engine on 1 cylinder.
Replaced the condenser. re- gapped the points again.. (touchy)
As for the torque on the flywheel.. Around 80 ft lbs.

Fired up and real smooth now. Just a quick bump of the key and it running. Not bad for a 40 year old motor.
May need a little tinkering with though. The boat planes and scoots alone. On the control. there is a blue mark. I've read this is a cruise range. I'v noticed that when I go past this point the engine seems to be sluggish and slows. When I back off to the cruise area of the control it picks up speed.

Not sure if thats the way it suppose to be.

Had the boat out for about an hour today..